Weighted insole



Nov. 5, 1963 R, P, GLYNN 3,109,245

WEIGHTED INSOLE FiledApril 6, 19612 INVENTOR BY Mfm ATTORNEYS United States Patent C 3,109,245 WEIGHTED INSLE Robert P. Glynn, 15.0. linx 6521, Memphis, Tenn. Filed Apr. 6, 1962, Ser. No. 185,598 11 Claims. (CI. 3o-2.5}

This invention relates generally to physical fitness, and is particularly concerned with the development of a humans strength, speed, and/or endurance. Specilically, the invention is directed to a weighted insole adapted to be inserted removeably in various types of shoes.

It will be apparent from the following description that the invention can be put to many uses. However, since the invention finds particular utility as used with athletic shoes, the same has been discussed hereinbelow with reference to such type shoes. At the same time, it is to be understood that the invention is not limited to this specific use but can be applied with athletic shoes of conventional type, golfing shoes, street shoes, or other forms of shoes.

In training for many sports, and under certain general physical circumstances, it is particularly desirable to develop the leg muscles, as well as the strength, speed, and/ or endurance of particular individuals. With respect to athletes, previous inventors have realized these factors and have suggested that some additional weight be provided on or adjacent the athletes feet so as to develop his leg muscles, speed, strength, and endurance. The prior suggestions along this line have taken various forms.

One prior suggestion has been to use bags filled with lead shot or the like, which bags are adapted to be strapped to an athletes ankles. Another suggestion provides for using a weighted spat adapted to be ailxed on the users ankle, while stili another suggestion previously made resides in construction of a special shoe having a weighted element or elements permanently fixed there-in. With the rst and `second of the aforesaid suggestions, there is some inherent discomfort to the user, as well as interference with normal leg and foot movement. With the third suggestion, the cost of manufacture of the special shoe becomes substantial, in addition to which the athlete is necessarily required to have an additional pair of shoes.

--\\ Thus, while prior inventors have recognized the deletic shoe to provide additional weight therein at the most remote point from the pivotal fulcrum of the hip or knee to gain full advantage of all possible leverage.

Still further, an important object of the present invention is to provide such a weighted insole incorporating a layer which will absorb the normal moisture existent there adjacent, and which will in addition provide a friction surface preventing foot slippage and blisters resulting therefrom.

An additional, yet further, and more specific object of the present invention is to provide such as insole which takes the form of a laminate comprising a base layer consisting essentially of a rubber composition having a densifying yagent disbursed therein, and a fabric cover layer vulcanized to the base layer during curing of the base layer so that the fabric layer is uncoated and serves as a moisture absorbent layer, as well as a friction pad reducing foot slippage.

,. ICC

Aside from the foregoing somewhat general objects of the instant invention, an important specific object hereof is to provide in such an insole a base layer comprising a rubber having a densifying agent disbursed therein, which rubber and densifying agent when cured yield a thin pad of comparatively high specilic gravity but possessing a flexibility to permit normal foot movement.

Still further, yet even more specific objects of the present invention include: (a) the provision of a weighted insole conforming with the preceding objects, wherein the densifying agent consists essentially of lead powder litharge; (b) to provide such an insole wherein the rubber composition having the densifying agent disbursed therein to form the base layer also includes a suitable curing agent which yields the desirable exibilities; (c) the provision of such an insole wherein the fabric layer is vulcanized with the base layer and comprises preferably a canvas material which is durable in use; (d) the provision of such an insole which has preferably planar opposed top and bottom faces, and side edges contoured to conform with a human foot and/ or to conform with the shape of the sole portion of a normal shoe whereby the insole can be readily inserted therein in overlying relation to the sole portion; (e) the provision of such an insole which is readily adapted for continued use in a normal athletic shoe, such as a basketball shoe, or the like; and (f) the provision of such an insole which can be inexpensively manufactured and made available for use to the normal athlete at a minimum cost.

In accordance with the basic aspects of the invention, there is provided a removable insole for an athletic shoe comprising a laminated body having opposed top and bottom faces and side edges shaped generally to conform to the peripheral contour of a human foot. The laminated body, as suggested from the brief preceding discussion, comprises a flexible base layer preferably formed of a cured rubber composition having a densifying agent disbursed therein in sufficient quantity to substantially increase the specic gravity of the rubber composition, and a flexible fabric layer secured to the top face of the base layer. The particular ingredient used in and for the ruber composition, as well as the particular densifying agent used in accordance with the preferred embodiments hereof, as explained more fully below, are of particular importance in attaining all of the aforesaid objects.

The invention will be better understood, and objects other than those set forth above will become apparent, when consideration is given to the following detailed description. Such description makes reference to the annexed drawings presenting preferred and illustrative embodiments hereof. In the drawings:

FIGURE l is a perspective view, partially broken away and partially in section, of an athletic shoe having a weighted insole constructed in accordance with the present invention removably disposed therein;

FIGURE 2 is a plan View, partially broken away, of the weighted insole shown in FIGURE 1; and

FIGURE 3 is a transverse sectional view of the insole shown in FIGURE 2, FIGURE 3 having been taken on the line 3-3 of FIGURE 2.

In FIGURE l, for purposes of illustration, a standard type of athletic shoe, such as normally used by basketball players, is presented. Such shoe is generally designated by the numeral 2, and includes a sole portion generally designated by the numeral 4, and an upper portion generally designated by the numeral 6. The sole portion incorporated in a conventional shoe of this type includes a suitable rubber composition sole member 8 having a suitable pad 10 disposed thereover. The upper portion 6, on the other hand, in a conventional shoe such as shown in FIGURE 1, comprises a series of canvas panels suitably joined together as along the seams i2, ist, and le, to form a foot encasing structure.

As is also conventional, the upper d is affixed to the sole pontion 4 as by stitching or the like, and the sole portion t carries at the forward edge thereof a. protective facing 13. If desired, as shown, a flexible toe protecting pad can be incorporated to cover the top toe surface,

The particular shoe which is shown in FIGURE. 1 and which has been described in some detail hereinabove, forms no part of the instant invention. lt is to be understood that such shoe has specifically been shown only for exemplary purposes, and that the invention can be applied to any type of athletic shoe, if desired.V

Now referring more specifica-ily to the invention, as shown in FIGURE 1, the shoe 2 has a fweighted insole 3u disposed therein. The insole 3i) is a laminated body, including a base layer 32 and a facing layer 34. Preferably, and as explained more fully below, the facing layer 34 comprises a fabric vulcanized on the base layer 32. The base layer 32, on the other hand, comprises a rubber composition having a densifying agent disbursed therein, so as to increase the specific gravity thereof.

The insole litiV is a unitarybody, in and of itself, and can be removably inserted Within the upper 6 of the shoe 2 shown in FIGURE l, so as to increase the weight thereof and thereby develop the leg muscles and endurance of an athlete. The thickness of the insole Stil can be varied to provide more or less weight, but preferably the thickness ranges between .l inch and '.25 inch. Within these limits, the insole can ready be inserted in any athletic shoe, without interfering with the subsequent insertion therein of the athletes foot.

t will be noted that the insole 3i) has opposed top and bottom faces, the top face being formed by the exposed surface of the fabric layer 34, and the bottom face being formed by the remote face of the base layer 32. The side edges of the insole are contoured to conform with the shape of the normal human foot, and/or the shape of the sole portion 4 of the shoe 2. Naturally, the shape of the insole will be varied slightly and the dimensions thereof will be altered, depending upon the size of the athelete yand the size of the shoe with which the insole is used.

In accordance with Ithe preferred embodiment hereof, the base layer 32 of the weighted insole is formed from a GR-S (butadiene-styrene copolymer) composition having litharge (lead monoxide) as the densifying lagent disbursed therein. Preferably, sulfur is used as the curing agent for .the composition, and is provided in suicient quantity to yield a suitable hardness and flexibility. As well known to those skilled in the art, an increased proportion of sulfur results in a sacrilice in flexibility, and similarly the use of a decreased proportion of sulfur results in a decreased hardness. Thus, the sulfur content can be varied in accordance with well known techniques to achieve the desired flexibility and hardness.

The use of litharge does not only yield an activator, but provides the necessary weight. Thus, in accordance with the invention, the activating effect of the litharge is but auxiliary to the use thereof for the purpose of increasing the specific gravity of the ultimate base layer form.

EXAMPLE 1 1 part of GRS 15001was mixed with 1G parts of litharge and .1 part of sulfur. After thoroughly mixing the ingredients to form a substantially uniform composition, such composition was placed in a mold and a layer of duck (8 oz.) was placed thereover. The mold was Lthen closed, and maintained at a temperature of 325 degrees F. for a period of 20 minutes. The mold was then opened, and the resultant product, in the form of an insole constructed in accordance herewith, was removed and cooled. Such insole was found to be durable in use, and to have a ilex ibility substantially equal to the iiexibility of Ithe normal basketball shoe sole (all parts by weight).

Zi/Iodifcations Although it has been found that the particular composition for the base layer set forth in the preceding example affords outstanding results, and although it has been found that the use of duck or canvas for the fabric layer yields the most desired final product, certain modiiications are contemplated by the instant invention. yit is important to understand, however, that regardless of the modification, the fabric layer 34 should be able toV absorb the normal existent moisture, such as is absorbed by the conventional insole pad in an athletic shoe. Moreover, the base layer should have a exibility compatible with the flexibility of `the sole of the particular athletic shoe in question. Still further, the densifying agent must be present in a sufficient quantity to substantially increase the specific gravity of the rubber composition alone.

Using a sufcient quantity of the densifying agent to double the specific gravity of the rubber composition is suit-V able for some purposes, but the preferred embodiment of the invention contemplates using a sufficient amount of the densifying agent to increase the specific gravity by at least three (3) times, and preferably four (4) times or more.

Although GR-S has been found to be most satisfactory, the basic rubber composition utilized can be neoprene, butadiene-acrylonitrile copolymers, natural rubber, or butyl rubber of the type disclosed in U5. Paten-t 2,356,- 128. Moreover, although sulfur has been set forth as the preferred curing agent, sulfur chloride or other suitable curing agents now in use can be utilized.

lf desired, accelerators, such as hexamethylene-tetraamine can be incorporated to lower the temperature and time required for curing. Also conventional anti-oxidants can be mixed with the initial base layer composition to retard the brittleness thereof.

The curing agent serves to provide a cross-linking between the polymers of the base rubber composition yutilized, and thus as suggested above, controls the hardness and flexibility. At the same time, the curing agent maintains, after the curing operation, the densifying agent in uniformly disbursed condition because of the cross-linking of the rubber composition which results from utilizing the curing agent.

Although litharge has been found to have the satisfactory properties, other densifying agents can be used, such as, for example, red lead, lead powder, or iron oxide. Regardless of the densifying agent used, however, the same is preferably pulverized into a tine powder form before dispersion in the base rubber composition. In any instance, the densifying agent should have a specific gravity of at least 5.0, and be present in -a sufficient quantity to ultimately render a base layer 32 having a specific gravity of at least 2, and preferably 3, or more.

Although the densifying agents can be 'varied as suggested, one particularly preferable modification provides for using lead powder having .a 325 mesh screen particle size as the densifying agent, and using a small quantity of `litharge merely sufficient to act in its conventional manner as an activator. This modification has proved particularly stable.

It will be understood that by curing the base layer with the fabric layer disposed thereover during the curing operation, the fabric'layer is vulcanized onto the base layer at the time of curing. This leaves an uncoated fabric surface to absorb moisture as well as a friction pad to keep the foot from sliding on the insole. The elimination of sliding results in the elimination of blisters and the like. Y

In addition to the various modifications mentioned in this section of this specification, it will be appreciated by those skilled in the art that the temperatures set forth in the above example are satisfactory for many conditions, but can be varied substantially. The technique of curing rubber composition is well known, and suffice it to say that the curing temperatures and time can be varied in accordance with the particular material used to produce a product possessing the desired characteristics.

Conclusion After reading the foregoing detailed description, it will be appreciated `that the objects set forth at the offset of the instant specification have been successfully achieved. Accordingly, what is claimed is:

1. A removable insole for a shoe comprising a laminated body having opposed top and bottom faces and side edges shaped generally to the peripheral contour of a human foot, said laminated body comprising a ilexible base layer formed of a cured rubber composition having means therein for rendering the specific gravity of said base layer at least twice the specific gravity of said rubber composition, said means comprising a densifying agent consisting essentially of a metal powder, and a fiexible fabric layer secured to the top face of said base layer.

2. A removable insole for a shoe as defined in claim 1 wherein said densifying agent consists essentially of lead monoxide and said cured rubber composition consists essentially of butadiene-styrene copolymer having sulfur therein in sufiicient quantity to render said base layer suliiciently flexible to permit normal foot movement when said insole is supported adjacent a human foot.

3. A removable insole for a shoe as defined in claim 2 wherein for every one (l) part by weight of butadienestyrene copolymer parts by weight of lead monoxide are dispersed therein.

4. A removable insole for a shoe as defined in claim 3 wherein said sulfur is present in an amount by weight of between .0l and .1 part for every one (l) part by weight of butadiene-styrene copolymer,

5. A removable insole for a shoe as defined in claim 1 wherein said densifying agent consists essentially of lead powder and said cured rubber composition consists essentially of butadiene-styrene copolymer having sulfur therein in sufficient quantity to render said base layer suiciently exible to permit normal foot movement when said insole is supported adjacent a human foot.

6. A removable insole for la shoe as defined in claim 1 wherein said fabric layer is formed of a canvas.

7. A removable insole for a shoe as defined in claim 1 wherein said base layer has a specific gravity of at least 3.

8. A removable insole for a shoe as defined in claim 7 wherein said base layer has `a thickness of between .10 inch and .25 inch.

9. A removable insole for a shoe as defined in claim 8 wherein said fabric layer is 'vulcanized onto said base layer.

10. A removable insole for a shoe as defined in claim 1 wherein the quantity of said densifying agent dispersed in said rubber composition is sufiicient to increase the specific gravity thereof by at least three (3) times the specific gravity of said rubber composition.

11. IIn combination with a shoe having a sole portion adapted to underlie a users foot and an upper adapted to encase a users foot and secure said sole portion thereunder: a weighted insole comprising a laminated body having opposed to'p and bottom faces and side edges shaped generally to the peripheral contour of a human foot, said laminated body comprising a exible base layer formed of a cured rubber composition having means therein for rendering the specific gravity of said base layer at least twice the specific gravity of said rubber composition, saidy means comprising a densifying agent consisting essentially of a metal powder, and a flexible fabric layer secured to the top face of said base layer.

References Cited in the le of this patent UNITED STATES PATENTS 381,579 Pratt et al. Apr. 24, 1888 1,517,861 Rosher Dec. 2, 1924 1,652,307 VHines Dec. 13, 1927 2,658,288 Scholl Nov. 10, 1953 2,748,502 Schol-l June 5, 1956 2,979,835 Scholl Apr. 18, 1961 FOREIGN PATENTS 580,159 Canada July 28, 1959 1,084,290 France July 7, 1954 27,394 Great Britain of 1898 728,075 Great Britain Apr. 13, 1955 

1. A REMOVABLE INSOLE FOR A SHOE COMPRISING A LAMI-NATED BODY HAVING OPPOSED TOP AND BOTTOM FACES AND SIDE EDGES SHAPED GENERALLY TO THE PERIPHERAL CONTOUR OF A HUMAN FOOT, SAID LAMINATED BODY COMPRISING A FLEXIBLE BASE LAYER FORMED OF A CURED RUBBER COMPOSITION HAVING MEANS THEREIN FOR RENDERING THE SPECIFIC GRAVITY OF SAID BASE LAYER AT LEAST TWICE THE SPECIFIC GRAVITY OF SAID RUBBER COMPOSITION, SAID MEANS COMPRISING A DENSIFYING AGENT CONSISTING ESSENTIALLY OF A METAL POWDER, AND A FLEXIBLE FABRIC LAYER SECURED TO THE TOP FACE OF SAID BASE LAYER. 